Higher Resolution Brings Richness To Digital Mona Lisa

The Mona Lisa never looked her best on computer screen. The detail was missing. Her smile was fuzzy, which put artists in a difficult position.

If they wanted to change Mona - color her purple, update her background, make her grin - they could do amazing things electronically. If they wanted to glimpse the richness of the original, they needed a photo or print.

Xerox has developed a solution for this unappealing tradeoff. By adapting technology used to make laptop computer screens, the company has created a high-resolution display with an image that looks as sharp on-screen as it does printed out on a good-quality laser printer.

The possibilities are huge. Want to search a map? An on-line version could show you the way with as much clarity as today's paper variety. Want to read a book on-screen? With resolution approaching that of a printed page, it should prove easier than it is today.

With really high-resolution screens, we might eventually turn from a race of Internet surfers to Internet readers.

There are, of course, a few hurdles to overcome before we get there.

First, to achieve the resolution of a 600 dots-per-inch laser printer, Xerox can only offer a black-and-white image. That's not a drawback for text. But showing off the bright colors of the Internet's World Wide Web, for example, means reducing the resolution.

Instead of displaying a black-and-white picture with 6.9 million points - called pixels - the Xerox technology in color can achieve only a little better than 1.7 million pixels. That's because it takes four pixels with special filters to make one full-color pixel. That's still far better than the 480,000-pixel screens that are beginning to appear on most high-grade notebook computers, although some companies, such as Japan's NEC, have begun selling 1.3 million-pixel screens.

Another obstacle is cost. Although the Xerox technology uses active-matrix liquid-crystal displays similar to those found in laptop computers, the company hasn't produced them in any volume. Xerox is spinning off the display research team into its own business, called dpiX (pronounced ''depicts''). The new venture will first try to capture high-end markets such as medical imaging and military avionics, where retrofitting the display in a cockpit can cost anywhere from $10,000 to $20,000.

NEC doesn't do much better. Its new screens cost $6,000.

The Xerox technology would allow pilots to view highly detailed digital maps, radar data, their tactical situation, and other flight information with far more detail and precision than they can now. According to Malcolm Thompson, dpiX's chief executive officer, the US military has some 6,500 aircraft that need to be retrofitted. The company already has a joint marketing and development agreement with Planar Advance, an Oregon display manufacturer, to supply the military with the new screens.

Eventually, company researchers expect their high-resolution system to spill over into other fields, such as commercial aviation, high-end graphics, and document retrieval. ''Anywhere with fine art and graphics is where you're going to see that first,'' says Dr. Thompson.

Prices will drop. And by then, computers may have improved to the point they can handle the extra demands of the high-resolution screens. The more pixels a computer screen has, the more power and speed it requires of the computer, reminds Bob Myers, senior engineer for displays at Hewlett-Packard's workstation systems division.

But one of these days our computers are likely to be as clear and easy to read as the printed page. Computers of that era may be shaped to look like books or newspapers. And on-screen Mona Lisas will retain all the richness of their enigmatic smiles.